Generally speaking, a wind tunnel used to test the aerodynamics of a vehicle includes a housing within which a vehicle to be tested is positioned. An air flow generator or mover such as a fan or blower is used to create an air stream that is directed through a contraction cone and a test section within which the vehicle is positioned. Air typically exits from the wind tunnel through a diffuser. In one known approach, six extremely large fans were positioned in a single common duct downstream of the diffuser for moving air through the test section. This common duct was connected to a single additional downstream diffuser. Wind tunnels may be of an open circuit design in which atmospheric design where air is drawn into the contraction cone and discharged from the diffuser back to atmosphere. Alternatively, wind tunnels may be designed to recirculate air in a loop or return flow configuration. A wind tunnel also includes instrumentation for measuring the desired information, such as the wind drag created by a vehicle.
It is common practice to include the entire vehicle in a wind tunnel during a test. In the case of tractor trailer combinations, one common approach is to include either the tractor alone or the entire tractor and towed trailer or shortened mock towed trailer with or without wheels in the wind tunnel. In this latter case, the wind tunnel must be large enough to receive the entire tractor trailer combination.
A need exists for a new and improved wind tunnel and associated methods for measuring the aerodynamics of vehicles, such as, but not limited to, tractors of the type which tow trailers.